Process and apparatus for joining at least two elements

Abstract

Process and apparatus for joining at least two elements, in particular an electronic component such as an LED with a substrate, such as a PCB. An imaging means divides a light beam into a plurality of partial light beams and images these partial light beams, forming a plurality of discrete light spots, which form a plurality of discrete material joining portions. The light beam is divided using a diffractive optical element (DOE) also enabling a beam shaping and beam processing. A plurality of material joining portions can be formed simultaneously enabling a high process rate. The method is suited for laser soldering of components, which are not exposed to high thermal loads, e.g. for forming electrical contacting portions of LEDs. These discrete light spots can also be used for material processing, in particular for simultaneously forming a plurality of preweakened material zones or perforations in a substrate.

1 . A process for joining at least two elements, comprising the steps of:
 providing a light beam;   imaging said light beam using imaging optics and dividing said light beam into a plurality of partial light beams such that a plurality of discrete light spots are formed for forming a plurality of discrete material joining portions between said at least two elements.   
   
   
       2 . The process as claimed in  claim 1 , wherein said imaging optics comprises a diffractive optical element which divides said light beam into said plurality of partial light beams by diffraction. 
   
   
       3 . The process as claimed in  claim 2 , wherein the joining portions are formed in a predetermined configuration, which is given by the configuration of the elements to be joined and/or by the geometric configuration thereof, and wherein the diffractive optical element divides said input light beam into said partial light beams in accordance with said predetermined configuration of joining portions and directs the same into different directions. 
   
   
       4 . The process as claimed in  claim 3 , wherein the diffractive optical element comprises a plurality of diffractive optical zones in accordance with said predetermined configuration of joining portions. 
   
   
       5 . The process as claimed in  claim 4 , wherein the diffractive optical zones cause at least one of: different intensities, different beam cross sections, different beam shapes and beam divergence of said partial light beams. 
   
   
       6 . The process as claimed in  claim 2 , wherein said light beam is emitted from a light waveguide and said imaging optics comprises an input lens and an output lens, wherein a beam diameter of said light beam or of said partial light beams is adjusted by varying at least one of: the distance between the input lens and the light waveguide and the distance between the input lens and the output lens. 
   
   
       7 . The process as claimed in  claim 6 , wherein the diffractive optical element is disposed between the input lens and the output lens. 
   
   
       8 . The process as claimed in  claim 1 , wherein the material joining portions are formed by one of: soft-soldering, soldering, welding and photo curing of an adhesive. 
   
   
       9 . The process as claimed in  claim 1 , wherein the joining portions are formed on contact pins of at least one electronic or opto-electronic component or of at least one connector by melting of a solder for joining the same with a carrier. 
   
   
       10 . The process as claimed in  claim 9 , wherein said carrier is a printed circuit board (PCB). 
   
   
       11 . The process as claimed in  claim 1 , wherein said light beam is a laser light beam. 
   
   
       12 . The process as claimed in  claim 1 , wherein said elements comprise at least one of: electronic components, microelectronic components, opto-electronic components, optical components, MEMS. 
   
   
       13 . An apparatus for joining at least two elements, comprising:
 holding means for positioning said elements or a substrate;   light source means for providing a light beam; and   imaging means for imaging said light beam and dividing said light beam into a plurality of partial light beams such that a plurality of discrete light spots are formed which cause a joining between said at least two elements at a plurality of discrete material joining portions.   
   
   
       14 . The apparatus as claimed in  claim 13 , wherein said imaging means comprises a diffractive optical element, which divides said light beam into said plurality of partial light beams by diffraction. 
   
   
       15 . The apparatus as claimed in  claim 14 , wherein said holding means positions said elements in a pre-determined configuration and said diffractive optical element divides said light beam into said partial light beams in accordance with said predetermined configuration and directs the same into different directions. 
   
   
       16 . The apparatus as claimed in  claim 15 , wherein said diffractive optical element comprises a plurality of diffractive optical zones in accordance with said pre-determined configuration of joining portions. 
   
   
       17 . The apparatus as claimed in  claim 16 , wherein said diffractive optical zones cause at least one of: different intensities, different beam cross sections, different beam shapes and different beam divergence of said partial light beams. 
   
   
       18 . The apparatus as claimed in  claim 13 , further comprising a light waveguide, wherein said imaging optics comprises an input lens and an output lens so that a beam diameter of said light beam are of said partial light beams is adjusted by varying at least one of: a distance between said input lens and said light waveguide and a distance between said input lens and said output lens. 
   
   
       19 . The apparatus as claimed in  claim 18 , wherein said diffractive optical element is disposed between said input lens and said output lens. 
   
   
       20 . The apparatus as claimed in  claim 13 , wherein said light source means is configured for providing at least one laser light beam.